title: The polyomavirus BK large T-antigen-derived peptide elicits an HLA-DR promiscuous and polyfunctional CD4+ T-cell response.
abstract: BK virus (BKV) nephropathy and hemorrhagic cystitis are increasingly recognized causes of disease in renal and hematopoietic stem cell transplant recipients, respectively. Functional characterization of the immune response to BKV is important for clinical diagnosis, prognosis, and vaccine design. A peptide mix (PepMix) and overlapping (OPP) or random (RPP) peptide pools derived from BKV large T antigen (LTA) were used to restimulate 14-day-expanded peripheral blood mononuclear cells (PBMC) from 27 healthy control subjects in gamma interferon (IFN-γ)-specific enzyme-linked immunospot (ELISPOT) assays. A T-cell response to LTA PepMix was detected in 15/27 subjects. A response was frequently observed with peptides derived from the helicase domain (9/15 subjects), while the DNA binding and host range domains were immunologically inert (0/15 subjects). For all nine subjects who responded to LTA peptide pools, the immune response could be explained largely by a 15-mer peptide designated P313. P313-specific CD4(+) T-cell clones demonstrated (i) stringent LTA peptide specificity; (ii) promiscuous recognition in the context of HLA-DR alleles; (iii) cross recognition of homologous peptides from the polyomavirus simian virus 40 (SV40); (iv) an effector memory phenotype, CD107a expression, and intracellular production of IFN-γ and tumor necrosis factor alpha (TNF-α); (v) cytotoxic activity in a chromium release assay; and (vi) the ability to directly present cognate antigen to autologous T cells. In conclusion, T-cell-mediated immunity to BKV in healthy subjects is associated with a polyfunctional population of CD4(+) T cells with dual T-helper and T-cytotoxic properties. HLA class II promiscuity in antigen presentation makes the targeted LTA peptide sequence a suitable candidate for inclusion in immunotherapy protocols.
authors.affiliation: Division of Transplant Pathology, Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15213, USA. ramaswamib@upmc.edu
authors.forename: Bala
authors.initials: B
authors.lastname: Ramaswami
authors.forename: Iulia
authors.initials: I
authors.lastname: Popescu
authors.forename: Camila
authors.initials: C
authors.lastname: Macedo
authors.forename: Chunqing
authors.initials: C
authors.lastname: Luo
authors.forename: Ron
authors.initials: R
authors.lastname: Shapiro
authors.forename: Diana
authors.initials: D
authors.lastname: Metes
authors.forename: Geetha
authors.initials: G
authors.lastname: Chalasani
authors.forename: Parmjeet S
authors.initials: PS
authors.lastname: Randhawa
mesh_terms: D000957:Antigens, Viral, Tumor / Q000276:immunology*; D001739:BK Virus / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D003429:Cross Reactions; D003601:Cytotoxicity Tests, Immunologic / Q000379:methods; D003602:Cytotoxicity, Immunologic; D058501:Enzyme-Linked Immunospot Assay / Q000379:methods; D006684:HLA-DR Antigens / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D017434:Protein Structure, Tertiary
chemical_list: D000957:Antigens, Viral, Tumor; D006684:HLA-DR Antigens; D007371:Interferon-gamma